Storage Rots

In storage, the following fungi attack ginger: Fusarium oxysporum, Pythium deliense, P. myriotylum (Sharma and Jain, 1977), and other (saprophytic) fungi such as Geotrichum candidum (Mishra and Rath, 1989), Aspergillus flavus (Geeta and Reddy, 1990), Cladospo-rium lennissimum, Gliocladium roseum, Graphium album, Mucor racemosus, Stachybotrys sansevi-eriae, Thanatephorus cucumeris, and Verticillium chlamydosporium (Dohroo and Sharma, 1992a). Geotrichum candidum caused complete rotting of inoculated rhizomes in 15 days at 25°C and 100 percent relative humidity (Mishra and Rath, 1989). The fungus A. flavus in association with ginger rhizomes was implicated in the production of carcinogenic aflatoxin (Geeta and Reddy, 1990). A. niger and Rhizoctonia solani have been associated with ginger rhizomes producing pectinolytic and cellulolytic enzymes during pathogenesis in inoculated rhizomes (Agrawal and Gupta, 1986). Under storage, different fungi have been found associated with ginger rhizomes that result in rotting and decaying of the rhizomes (Dohroo, 1993). Different types of storage rots (Table 8.11) have also been reported by Dohroo (1995 a).

Control Measures

Under storage conditions, postharvest dip treatment of Aureofungin (0.02 percent) and Benlate (0.2 percent) provided better control of the disease (Haware et al., 1973). Treatment of rhizomes with T viride has also been observed to give more than 80 percent control of rhizome rot caused by P. pleroticum (wet rot) and F. equiseti (dry rot) by Dohroo and Sharma (1984). Sharma and Dohroo (1991) reduced the disease incidence under storage from 71.4 to 18.2 percent by steeping the rhizomes in carbendazim (0.1 percent) for 60 minutes. Bavistin (carbendazim) and carbendazim plus Dithane M-45 inhibited growth of F. oxysporum f. sp. zingiberi under in vitro conditions (Sharma and Dohroo, 1991).

Prestorage chemical treatments reduce the incidence of storage rots (Okwuowulu and Nnodu, 1988). They have observed postharvest (pre-storage) application of benomyl (750 ppm a.i.) and/or gibberellic acid (150 ppm) to be most effective in controlling the rots.

Dipping of rhizomes in imazalil or prochloraz at 0.8 g a.i. per liter and then storing at 10°C gives good protection against the infection with fungi such as Botryodiplodia, Aspergillus, Diplodia, Fusarium, Rhizoctonia, and Pythium in storage (Grech and Swarts,

Table 8.11 Pathogenicity of fungi associated with storage rot of ginger

Fungi

Type of rotting

Rot (%)

Incubation period (days)

Rotting after 25 days

Pythium ultimum Trow

Soft rot

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